Am I worried about M4 for nothing?

Look at your blade every day. If you notice spots developing just get flitz and rub them out with a rag. It isn’t going to rust unless you leave water on it and neglect it for days. Wipe it down with a rag if you cut anything wet and move on with life. I would do the same thing with stainless as a habit anyway so it’s no different for me. The benefits of M4 outweigh any potential inconveniences from potential rust.
 
Another Shepherd said:
Not all day, but for a couple hours a day, that's what I do in the summer, and D2 (which Larrin rates at 4.5 for corrosion resistance) rusts so much for me that I quit buying it. Larrin rated M4 at 4 for corrosion resistance, so I would never buy that. I do use 3V (5.5 for corrosion resistance) in the winter when we have occasional rain, wipe it off carefully, no problems so far.

It may be that some people have saltier sweat than others, and that could make a difference in how much a knife rusts.
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Some people absolutely do have saltier sweat than others. A friend of mine who is delivers mail sweats too much for M4.

I would've expected D2 to be higher corrosion resistance, given it's touted as semi-stainless with how high it's Cr content is. Givenchow many variations there are of it, and heat treat variarions, makes me wonder some if the HT isn't the best to keep corrosion resistance up. Either way, I would avoid it too if it was rusting on me easily.

Some people can get stainless steel to fust from sweat. I like to carry a knife while out on bicycle rides and 8cr rusts pretty easily, IME, so I've stuck to salt series knives now. Native 5 salt has been a great knife to have since it came out several years ago.

One big thing going for the knife specifically mentioned in the OP is that the blade will be coating, and BM's coating tends to hold up well, IME.

As an aside, I know one guy who works maintenance in a wet environment and uses an O1 steel knife regularly. He uses frog lube and says he hasn't had any major rusting issues at all, just spotting here and there that get imparted into the layers of patina with use. A little lube helps a lot.
 
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bikerector said:
Some people absolutely do have saltier sweat than others. A friend of mine who is delivers mail sweats too much for M4.

I would've expected D2 to be higher corrosion resistance, given it's touted as semi-stainless with how high it's Cr content is. Givenchow many variations there are of it, and heat treat variarions, makes me wonder some if the HT isn't the best to keep corrosion resistance up. Either way, I would avoid it too if it was rusting on me easily.

Some people can get stainless steel to sweat. I like to carry a knife while out on bicycle rides and 8cr rusts pretty easily, IME, so I've stuck to salt series knives now. Native 5 salt has been a great knife to have since it came out several years ago.

One big thing going for the knife specifically mentioned in the OP is that the blade will be coating, and BM's coating tends to hold up well, IME.

As an aside, I know one guy who works maintenance in a wet environment and uses an O1 steel knife regularly. He uses frog lube and says he hasn't had any major rusting issues at all, just spotting here and there that get imparted into the layers of patina with use. A little lube helps a lot.
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In my experience this is true. Now, regarding knives...... :eek:
 
bikerector said:
Some people absolutely do have saltier sweat than others. A friend of mine who is delivers mail sweats too much for M4.

I would've expected D2 to be higher corrosion resistance, given it's touted as semi-stainless with how high it's Cr content is. Givenchow many variations there are of it, and heat treat variarions, makes me wonder some if the HT isn't the best to keep corrosion resistance up. Either way, I would avoid it too if it was rusting on me easily.
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It was SOG knives with Cryo D2 made in Taiwan that I had so much trouble with 5 years ago.

bikerector said:
Some people can get stainless steel to sweat. I like to carry a knife while out on bicycle rides and 8cr rusts pretty easily, IME, so I've stuck to salt series knives now. Native 5 salt has been a great knife to have since it came out several years ago.
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I like the Pacific Salt and plain Salt knives with LC200N, although some of them have very stiff action. My Gerber Strongarm with 20HC gets sweaty inside the sheath, but not a single rust spot so far.

bikerector said:
As an aside, I know one guy who works maintenance in a wet environment and uses an O1 steel knife regularly. He uses frog lube and says he hasn't had any major rusting issues at all, just spotting here and there that get imparted into the layers of patina with use. A little lube helps a lot.
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Yes, Frog Lube had done very well in tests. I use it on some of my wife's knives. She had terrible corrosion on a Higo no Kami with Super Blue steel. I had to grind off about a quarter of the blade width to restore the edge. But since the Frog Lube, no rust at all.
 
Citori said:
YMMV but this is a PM2 with CPM-M4. My wife has been using it to take up the weed barrier in our back yard, which full of grit and is wet from being sprinkled. She has been doing that with it for a few weeks and other than wiping a couple of dirt clods off before I took the photo, it hasn't received any care.

That amount of rust doesn't affect its functionality. There is a little on the edge bevel but it is (at this point) shallow enough that it comes off on first use and I can't tell it was there. I am working on the other side of the yard but using a cheap Fishers knife, some kind of stainless, and it looks better but cuts worse.

WETPM2.png
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Pretty sure women can just look at knives and mess them up. I've learned the hard way, now have cheap stainless victorinox paring knives I keep in the kitchen as a distraction ploy.
 
Worrying does nothing except make you sad, use M4 like anything else, if it changes colors on ya, use flitz. Don't leave it in water or pasta sauce, you're good
 
Whipe the blade after use or at least in the end of the day.

And, this is important, keep the pivot oiled cause here you cannot see rust develop unless you take the knife apart.

A quick spray with f.ex ballistol once a week should keep the pivot protected.
 
What a great suggestion for the spray oil. My Spyderco Mantra II will get a spray. And maybe get its "flip" back.
 
Wipe it down with a little CLP every so often and you’ll be fine. M4 is indeed a carbon steel, but it isn’t bad enough that you can sit and watch it rust.
 
I like M-4 enough that I just don't care if it gets stained.
Close your eyes for a moment...kiss a beautiful girl(boy).

Now open your eyes, and reflect...did it get you excited? Would it matter if you opened your eyes and saw something "unexpected"? Rust and stains won't affect the function of cutting. Is your knife a cutting tool, or just something to show off?

M-4 is tough, and holds an edge forever; just the kind of things a KNIFE should do. Now if your knives need to be jewelry and bling*#%, then get another type of knife, or spend a buncha time making sure they don't look like a working knife.
 
I like that I can have a 15 dps edge on my native chief and not have to resharpen it after I use it once. M4 is worth it and patinas are cool. But I don't have anything over $500 anymore and I use everything I have.
 
I wouldn't worry about it. I live in the PNW near the ocean and don't have problems with rust. That includes steels like Maxamet, K390, and M4. Just make sure you always clean your blades and keep a light coat of oil on the non stainless ones.

Me, I'm a little bit OCD about my knives. I don't even like finger prints on them, lol 😋
 
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